How can I improve card design?

I’m a Biology teacher also interested in making things look good. I am making a lecture on zoology and decided to set up the key information in cards – so students may take a screenshot and use them for revision.
I did my best, but the design still looks crappy for me – especially the bottom half. Here’s an example (also an actual slide from presentation):
enter image description here

Where can I find a large palette / set of contrasting colors for coloring many datasets on a plot?

I need large set (20 and more) of contrasted and easily visually-distinguishable colors for coloring different datasets on a scientific plot (the set of colors should not include white or black, and colors should be as bright as possible).